The present invention relates to a needle drive mechanism for sewing machines, and more particularly to a mechanism which will permit relative movement of two sewing machine needles to stitch a fabric, for example, with a two thread interlocked chain stitch.
Sewing machines traditionally have used a mechanically driven needle, though which a stitching thread passes. Vertical movement of that needle and thread through a fabric to be stitched is coordinated with a looper device, situated below on the blind side of the fabric, to form an interlocking stitch in the fabric. This type of construction requires a relatively massive frame for the sewing machine, to ensure that, during operation, a precise positional interaction between the needle and the looper. Othewise, vibration of the machine during operation would prevent the precise interaction required between the looper and the needle. As well, the traditional cantilever structure required in such traditional sewing machines limits the application of such sewing machines to the edges of cloth. A wide cloth cannot be readily stitched in a central location.
Prior art references, showing such traditional sewing machine constructions, involving multiple needles having relative movement with respect to each other, include Taubert U.S. Pat. No. 2,058,271 issued Oct. 20, 1936, Sigoda Canadian Pat. No. 458,989 issued Aug. 16, 1949 and Noble Canadian Pat. No. 45,179 issued in September, 1887.
It is an object of the present invention to devise a drive mechanism for a multiple needle sewing machine which will enable the sewing of a stitch such as a two thread interlocking chain stitch in a fabric. It is a further object of the present invention to provide such a drive mechanism which will avoid the need for a looper or other mechanism on the other, blind side of the fabrib being sewn, thereby reducing the need for a massive frame structure and avoiding the need for a span limited cantilever construction.